Telephone-exchange system



1,470,451 T. KCRTHAUER TELEPHONE EXCHANGE SYSTEM Filed Dec. 9. 1921 8 Sheecs-Sheell 1 Oct 9 1923.

oct. 9,1923. y 1,470,451 A T. KORTHAUER TELEPHONE EXCHAGE SYSTEM Filed Dec. 9, 19721 8 Sheets-Sheet 5 *Im/En ur- T. KORTHUER TELEPHONE EXCHANGE SYSTEM Oct. 9 1923.

` z sheets-sheet 4 w Filed Deo; 9, 1921 VIH T. KORTHAU ER A. TELEPHONE EXCHANGE SYSTEM Filed nec. 9, 1921 8 Sheets-Sheet 5 EYE-f5.

Oct. 9 1923.

T. KORTHUER TELEPHONE EXCHANGE SYSTEM Filed Dc. s. 1921 8 Sheets-Sheet 6 TZiEnE/'Ur Kuhuer' Oct; 9 1923. 1,470,451.

T. KORTHUER .TELEPHONE EXCHANGE SYSTEM Filed Dec:l 9. l921` 8 Sheets-Sheet -InUEz-z Dr Thennrnr Knhuer HIT-H5 Oct. 9 1923.

T. KORTHUER TELEPHONE EXCHANGE SYSTEM Y e sheets-sheet e l Filed Dec. 9, 1921' UNITED] STAT inganni orifice.

THEODOR KORTHUER, OF SIEMENSSTADT, NEAR BERLIN, GERMANY, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, Oli CHICAGO, LLINOIS, A CORPORATION OF ILLINOIS.

@unanimita-EXCHANGE svsriiivi.

Apiiication filed December 9.1921. semi No. 521,264.

To all fia/20m. it 'may concern Be it known that I, Tiiiionon Koirrniiunn, a German citizen, and resident of 9, Schuh strasse, Siemensstadt bei Berlin, Germany, have invented certain new and useful Improvenients in Telephonelxchange Sys-` tems, ol which the following is a specification.`

The invention relates to telephone sys# tems with differently operated exchanges,

the object being to facilitate connection between subscribers belonging to exrhanges operated in diliferent ways. consists in that trunk lines are directed by l5 switching operations on the part of the operator at the calling subscribers exchange, whereby, at the same time an impulse transmitting device is connected up, and

the Control of the impulsesV for automatically setting a route selector of the trunk line is controlled. In this way the necessity for any special attention .to the impulse device on the part` oi. the operator is obviated.l .The switching operations to beperformed by theepera' tory are reduced to a minimum, and consist, 'for instance, solely inplugging the trunk.- line jack.` The invention presents special advantages for telephone systemsin which 3U it is impracticable to reach all the other exchanges 'from one exchange. In such cases the `route selector is located in an exchange from which all the others can be reached.

According to the invention, the switching operations of the operator preferably set in action a special selecting switch which connects up the impulse sender to the trunk line, starts it and directs the transmission ot the impulses. In telephone systems in which the trunk lines are reached through jacks, it is advisable to allot to trunk line yseveral jacks at an operatingposition, and to directthe trunk line by plugging one of these jacks. y y `according to the invention, in the case of telephone installations onthe singleplug system, the directing oi? a trunk line, after the same is taken into use, is elif-coiled by operating a key, there being only one `set` of keys for this purpose.` to all the trunk lines of an operating position..

The trunk line jacksfat an operating po-.

sition are divided into groups correspondrlhe invention f ing to the different exchanges, and the inipulse sending device is provided with a Contact for .each of these groups.` The Iswitching arrangement alloted to the jack groups, `or the lines coming from the rdirect#` ingkeys to the impulse device, are prefer` ably connected up 'in inverse numerical order.. A particularly advantageous embodiment consists in setting the impulse sending device (after the position selector has been set on a jack) on the `contact corresponding totliejack group taken into use by the position selector. 'The switching-in of the iin`- pulse sender Jfor transmitting impulses during its continued movement to its initial position isr effected after a route selector' has been connectedfup. y rllvo embodiments of the invention are diagrammatically illustrated in the drawings. Fig. i. shows the grouping Vof "the jacks andof the selecting switch for connesting up the impulse sender to ra trunk' line and the numerical impulse rreceiver adapted to be" connected up tothe trunk lines. .Figs 2-5, inclusive, illustrate in detail the Vdirection traversed, by the current in the arrangement according to Fig. `l. Figs. 6-S,`inclusive, represent ay circuit arrangement orlinstallations on the singleplug system. `Figure 9 shows a modified arrangement iior giving theloperator a distinctive clearing signal.

Thefsubscriber 7L, (Fig. l) belonging to the manual exchange lVis provided at the Aposition with the usual calling signal and the answering Vjack AKl. The operator answers, in known manner. after inserting the answering plugv Astp. Different groups 'lil of trunk-line jacks are situated in the iack field of the position. Through the jack K, connection can beset up with exchange lll by way of one of thejacks VKQ. Ift-he call- Accordingly, its wiper 504 finds itself in group 1-in fact on contact 505. By this means, the impulse sender, consisting of an impulse selector JW, is caused to set itself on the contact 506. At the impulse selector JW, the lines coming from the position selector PIV are connected in 'inverse order to the numerical arrangement ofthe jacks. Consequently` assuming the route selectors to be provided with ten groups of lines each, the group 1 will be situated on the tenth contact of the impulse selector. After the first selector I GIV 503 has been connected up the set impulse lselector JW is caused to continue running until it reaches its position of rest, thus sending impulses through the trunk lines to set the route selector I.GW 503. Since thel impulse selector JW is set on the tenth Contact, the position of rest is reached in one step and only one current impulse is sent out and theroute selector is accordingly moved on to the first contact group, the lines of which lead to the exchange III. In this cont-act group 'K the route selector IGW 503 automatically hunts for a free line, the operator at exchange III then completing the connection in known manner. After the setting of the route selector IGIV 503, the position selector PW and the impulse selector JIV are released, and can be used for another connection.

In detail, the operating of an installation of this kind according to Figs. 1-5, inclusive, proceeds as follows:

The exchange IV (Figs. 1 and 2) serves, in addition to manual subscribersfor example ftp-for automatic subscribers, for expample s4, who are enabled by switching operations performed by the operator to connect themselves up with subscribers of an automatic exchange (for example VI) or with a group of automatic subscribers of the manual exchange IV.

Assuming, in the first place, that the manual subscriber 71,4, desires to be put through to the subscriber It, of the manual exchange III, when the receiver at the sub-station it., (Fig. 2) is removed, thecalling relay Ar1 operates by current passing through the subscribers lines a, and connects up the calling lamp AL, at the working contact 1; the

lamp AL1 lights over the circuit battery, call lamp ALI, contacts 2, 1 and earth. The operator at position A of exchange IV inserts the plug AStp into the corresponding answering jack AK1 thereby energizing the cut-offrelay TR which opens the Contact 2, so that the call lamp ALl goes out. The supervisory signal lamp SL1 does not light up, the resistance of winding I of the relay TR, being, too high. y

After answering, the operator inserts the connecting plug VStp in the trunk-line jack VK2, thus closing the contact 3, and connecting up the starting relay An as follows;

earth, contact 3, upper winding of relay R3, contact 4: resistances 5 and 6 relay An to battery. The relay An completes at its contact 7 the circuit for the motor magnet D3 of the position selector PIV. When the wipers of the position selector PW driven by the magnet D3 encounter the trunk line of the plug ed jack VK2 the testing vrelay P is energized in the following circuit; battery working Contact. 8, windings I and II of the testing relay P, wiper 9, contact 10, resistance 5, contact 4 upper winding of relay R3, and contact 3 to earth. The relay P operates, breaking the circuit of the rotary magnet D3 at the contact 11, and short circuiting its high-resistance windino' I at the Contact 12.

The `rotary magnet D5 of the first pre-selector I.VW is connected up, through thc contact 13 of relay P as follows: Earth, contact 13, wiper 14, bank contacts 15, relay contact 16, rotary magnet D5 and its interrupter to battery.

vVhen the first pre-selector I VVV has found a free second pre-selector II.V`W, the testing relay 'I3 is energized as follows; earth, working contact 17, of relay P, Fig. 5, wiper 13 bank contact 19, windings I and II of the relay Tm lower winding of relay R3, c lead and test wiper of the first pre-selector LVIV, winding I of relay R2, contact 20, winding II of relay R2 to battery. By opening, its contact 16, relay T..l breaks the circuit of the motor magnet D5, and short circuits the winding I of relay T3 at the contact 21, thus guarding the engaged second pre-selector IIVIV from being taken into use by any other first pre-selector IVW. At the second pre-selector IIVV the relay It2 completes the circuit for the motor magnet D6 at its contact 22, and prepares at contact 23, the circuit for the testing relay T5. When a free route selector IGVV has been found, the testing relay T5 is energized in the following circuit: earth at contact 13 of relay P, Fig. 5, wiper 14, bank contact 15, relay contact 21, winding II of relay T3, lower windingof relay IQ, c conductor and test wiper of pre-selector I.VVV, winding I of relay R2, contact 23, windings I and II of relay test wiper of pre-selector II.VVV, c conductor of selector IGVV, contacts 2%, 25,windingI of relay V3, winding of relay C, to battery. The relay T5 breaks the circuit for the rotary magnet DG at the vcontact 26, disconnects the windingII of relay R2 at the contact 20, short-circuits the winding I of relay T5 at contact 27, and switches the speaking leads and l) through at the contacts 28 and 29.

The setting of the position selector PW on the plugged trunk-line jack VK2 completes the'circuit for the motormagnet D4 of the impulse selector J IV as follows: earth, contact 30 of relay P, rotary magnet D4, contact 31, interrupter to battery. IVhen the impulse selector JW finds the jack group taken into use by the position selector PW, the testing relay P1 is energized in the fol-V lowing circuit, battery, windings I and II of relay P1, wiper 32, bank contacts 38, 34 wiper 35 of position selector PIV, contact 36 to earth. 'Ihe relay P1 operates, shortcircuits its winding II at its contact 39 and locks itself energized over contacts 36 and 37, wiper 38 and contact 39.

In the first selector IGW the relays V3 and C1 are energized. Moreover, the relay Y, F ig. 2 is connected up in the impulse selector JW, circuit as follows: eartheIGW selector shaft back contact 40, contact 41,l

b-lead, contact 29, b-line wiper, Contact 411, winding I of relay T4,bank contact 42, wiper 43, contact 44, relay Y and contact 45 to battery. In this circuit the relay Y alone operates and not the relay T,the resistance of relay Y being too high. Ihe relay Y opens the contact 44 and thereby inserts the resistance 46 in its own circuit. Moreover at the contact 47, the relay J is energized through the contact strip 48 and wiper 49. The relay J completes the circuit for the rotary magnet D, through the contacts 5U and 51 and at contact 511 sends out an im-` pulse to the first selector I GrIV as follows earth, contact 511,wiper 52, bank contact 53, contact 54 of relay 'I4 a-lead, contacts 28,400, windingI of relay A, to battery. The relay A, completes the circuit for the lifting niagnet H at the contact 52 as follows: battery, lower winding of relay Vwflifting magnet H, contacts 52 of relay A1, 53 of relay VM 54 of relay C, to earth. By this means the relay V3 is kept energized duringa series of impulses, even after the opening of the contact 25. Through the contact 55, whichk is closed at the first lifting movement, the winding II of relay C, is connected up.

The motor magnet D, of the impulse sek lector JIV short-circuits the impulse relay J at the contact 56, thus n'iaking this relay release; and consequently the circuit for the rotary magnet D,l is broken at Contact 50, and that for relay A1 at contact 511.` In case the wipers of the switch JW do not reach a position of rest upon the above operation of the associated motor magnet, the relay J operates again in the above described energizing circuit, and sends' another impulse to the first selector IGJV. This cycle repeats itself until the impulse selector JW has reached its position of rest.

In the present case, however, the position of rest is reached upon the first operation of the motor magnet D4 after it is restarted, whereupon the relay J is disconnected and the relay Y is short circuited over the wiper 49 and contact 57. The relay Tg, is now energized through contact 45 of relay P1 wiper 49, contacts 57,44, 4wiper 43, bank contact 42. Relay T4 disconnects the position selector PW by opening the Contact 4; and connects up its winding II by closing the contact 58, and, by closing the contact 59, switching through the test conductor c from the trunk line jack VK, to the .first selector IGIV.

In the l'irst selector IGW the relay V3 becomes released when the impulse comes to an end, and connects up the rotary magnet I)G as follows: battery, rotary magnet D6, contacts 60 of relay A, 61 ofrelayV 62fof relay P2, 63 of relay C1, interrupter to earth. VVh'en the first selector IGIV finds a free line, the following circuit is set up; earth, winding I of relay P2, winding II of relay Al, Contact 64, test wiper'of the first selector IGIN, windings I and II `of relay TR3 to battery. The relays Peand TB, operate, but. owing to the high-resistance winding I of relay T133, the relay A, cannot operate. The relay .P2 breaks the circuit of the rotary magnet `DG at the contact 62, and short circuits its own winding I through the contacts 650i' relay C, and 66 of relay P2. The

holding winding II of relay P2- is connected up at its contact 67. 'In addition its contact 41 is opened, and its contacts 68 and 69 are closed, thus switching the. speaking leads cz., Z", through to the `line that has been found disengaged.

At the contact 691,`the relay TB, of the seized trunk line completes the following circuit; battery, contact 691, relay LBL., Ulead ofthe cord circuit at position B, re# lay HSR to earth. The relay HSR at its Contact. connects up 'the .relay SR1, and thefrelay SR1 connects up the clearing sig nal lamp BSL, (acting in this case as call `lamp at the B position) through the con-v tact 73 of the auxiliary relay HR, by opening thecontact 71 and closing the Contact 72. The operator at B enquires, by throwing over the speaking key 74 in known manner, and tests the multiple jack VK1 of the desired subscriber 71,3. If the line is free, the `operatm inserts the plug VStp1,`thus completing the circuit.; battery, rel'aylBr,

60,fprevents the relay AB from operating.`

The relay H, opens its contact 73 thus puts out the call lamp BSL, at position A further circuit for this lamp is prepared by closing the contact 78. In addition, the

v.relay H, completes, at its contact 88. the y circuit for the calling relay Px., which is energized intemnittently through an interruptor, and sends ringing currentover the subscribers line at its contact 84 and 95.

winding ll of relay C, causes the relay R,

of the first preselector I VVV to operate. The relay R, closes its contact 189, and short circuits the resistance 92, thereby increasing the current through the jack sleeve 90 and the sleeve 91 of the calling plug VStp, se that the clearing-signal lamp SL2 flashes in unison with the intermittent operation relay PR. The flashing of the lamp SL2 indicates to the operator at A that ringing current is being sent over the wanted sub- 'scribers line. l .If the wanted subscriber lz., answers, the relay Ar,L operates and opens its contact 82,

thus disconnecting the winding Il of relay TR, and reducing the current through the winding l ofk relay SR: s o that the eil'ect ot this winding is rendered equal to that ot yits differentiallyv connected winding ll.

Thereby causing its armature to fall back connecting up at Contact 80 the circuit preriously prepared, at contact 93 of relay Hrl, for the,- relay AB which connects itselt up, at contact 94 and contact 95 of relay SR, to a holding circuit dependent on SR1. T1 e relay AB at its contact 96, breaks thecircuit for the ringing relay PR, and at its con- *facts 97 and 98 switches the speaking leads into the B cord circuit.

`When the calling subscriber hangs up his receiver at the end of the conversation, the relay ARl releases and at its contact 99, connects up the low-resistance winding Il of relay TR, parallel with its high-resistance winding I. By this means the current through the sleeve of jack 100 and contact 101 of the yanswering plug AStp is increased so that the clearing signal lamp SLl lights up. then the called subscriber hangs up his receiver, the relay All4 releases and closes its contact 82 and connects up the winding Il of relay TR4 in parallel with its winding I so that the relay SR2 operates. This relay completes, at its contact 81, the circuit prepared for' the relay LR, at 81. The winding l of relay TR, is shortcircuited at the contact 88, and the current in the lead c, is thereby increased so that the relay A1 is now energized. This relay closes its contact 141 and thus brings into operation the relay R3 of the preselector I VlW which closes the contact 189. The clearing* signal lamp SL,I lighting up in consequence.

The operator at A takes the plug VStp out of the trunk-line jack VKZ, thus depriving the ener izing circuit of the relays T3, T4, T5 and of current. The relay C, opens at its contact 65 the circuit for the relay P: and closes, through the contacts 102 and 103, the circuit for the vrelease magnet M of the first selector' LGV, the latter being released. By opening the Contact Gel, the relay TR., is released, opening the Contact G9 and thus causing the relay HSR to fall back. The relay HSR disconnects, at the contact 70, the relay SR1, which completes, at the contact 71 vthe circuit prepared for clear-` ing the signal lamp `BSL at the contact 78.

The. B operator takes the plug SVtp out of the jack VK, of the called subscriber, whereupon all the switching devices used are again in their normal position.

If an automatic subscriber a, of the manual exchange lV wishes to get through to a subscriber of the automatic exchange VI, he calls up the manual exchange IV in the usual manner, by taking down his receiver. After the call lamp AL2 has lit up, the operator inserts the answering plug AStp into the jack Al2 and answers in known man` ner, and then inserts the connecting plug VStp in the auxiliary jack HK2 allotted to the line ot the automatic subscriber S4. By the closing of the jack contact 111, the rotary magnet D of the first pre-selector TVV allotted to the subscribersline is connected up as follows: earth, contact 111, conductor 112, armature 113 and its working Contact of the line relay AR2 contact 141. rotary magnet D to interrupter and battery.A Vllhen the first pre-selector LVXV finds a free second pre-selector ILVV the energizing of the cut-ott` relay T1 switches Ythe speaking line over from the answering jack Ak2 to the line wipers of the pre-selector at the contacts 115 to 118, inclusive. The first rotary movement or' the lirst pre-selector LVV opens the contact 119 through which as will be described laterthe two clearing signal lamps SL, and SL2 ol the cord circuit'are connected up at the end of the conversation. The second pre-selector ILVWY is connected up inthe known manner. F rom the second pre-selector LVW' as can be seen from the drawing the same trunk lines can be taken into use as can be reached by the operator at A through the trunk-line jack VK, and the pre-selectors LVW and ILVV. When a trunk linea .is taken into use by an automatic subscriber, however, a repeater Ue is connected up, but not when the trunk line is taken into use by the operator. Taking the repeater Ue into use connects up therein, through the lead c, the contact 181, and the resistance 132, the relay C3 which closes its contact 133 and thereby switches the c-lead through to the first selector LGV. In trunk lines taken into use by the operator, the Contact 131 oit the relay C, is opened, so that the test wiper of the second pre-selector ITVW does not lind any potential on these engaged lines. At the repeater Ue, the lbridge relay' A operates after the speaking leads have been switched through, and connects up the release relayfl1 at the contact 120. This relay switches the c-lead through at the contact 134, lthe relay C, being short-circuited.

When the subscriber a, sends out the im* pulses li'or setting the irst selector lGl/V the relay A1 is controlled through the lcontacts 121 and 122.y The setting of the first selector I GlV' then proceeds in the known manner. y

y When the subscriber hangs up his receiver at the end of the conversation, the set selecting devices are released by the opening of the contacts 123, 124 and 134 at the repeaterlle. The opening of the contact 134 deprives the relays CUT2 and T1 o1e TGW, TTVW, and LVW, respectively, of current. The relay C, releases the set numerical current impulse receiver in the manner already described, by closing the Contact 102 and opening the contacts 64and 65.

By depriving the `relays T., and T1 of current, both the pre-selectors ILV'W and VVV are released. `The `first pre-selector LVWreturns to its `normal position and thereby connects up the two clearing signal lamps SL, and SL, as follows: earth, contacts 119, 123` on the one hand through the winding II of relayTRZ, jack sleeve 126, plug contact 101,(clearing-signallamp SL, to battery, and `on ythe other hand through resistance 127, jack sleeve 128, plug contact 91, lamp SL, to battery. Hereupon the operator takes `both plugs AStp and VStp out oie the jacks AK2 and HKZ. y i

In thef embodiment of thetinvention. according to Fig. 3 the A positionl is arovided with only one answering plug `Stp, to which is connected a line leading -to a first pre-selector IVW. The call of the subscriber h4 proceeds in the following manner: Plugging the answering jack with the plug ASTP operates the relay R, which causes the position selector PW to move o n to the answering plug that has beentaken 1 nto use. 1121er instance, the subscriber It, wishes vto be `put through to a subscriber of themanual exchange Ill., the operator presses the key Tal. This switching operation `on the part ot' the` yoperator must ber regarded as equivalent to plugging a trunk line. Pressing this lkey directs ,the trunk line that is taken into use, since it determines the number oi? current impulses to be sent out. The setting, of the position, selector `PVV prof, ceedsiin the manner described with refer-` ence `to Figs. .2 and 2L and `needs no 'further explanation. lThe lsame also applies to the setting of ythe rst and second pre-selectors LVW'f-andITVV Since the operatordoes not :directgthe trunk line until after taking y into use and answering, an appreciable amount offtime elapses after the plugging in and the starting of the preselectors and before the starting of the sending switch JW responsive to the operation of the key Tal, during which a route selector is connected up` beforejtransmission or" impulses can take place. i Consequently, no specialdevices are needed for delaying the connecting up of the impulse device until after a route selector has been connected up. y f

Pressing the key Ta1 connectsiup the rotary magnet D1' of the impulse selector as follows: earth, contacts'141 and 142, rotaryy magnet D1, contact 143 and interrupter to battery. lVhen the impulse selector finds the depressed key Tal, the relay P1 is energizedas i'ollowszearth, key kcontact 144,

bank contact 145, wiper 146, relay l?, to battery. The relay P, closes the `contact 147, andthereby maintains itself energized iudependently of the key `Tas, by way of the wiper 148 and earth to contact 149. l), also opens the contact 143 and closes `151 the impulse relay J being thereby energized as follows: battery, contact 151, wiper l152, contact153, relay fl, contacts 142 and 141` to earth. At the contact 25,0, the relay J sends' out an impulse to theselector `(LGW) over the .wiper 251, and thisy `relay also ,connects 'up the rotary magnet Dl through the contact 153. The impulse selectorr moves one step. The rotary magnet D, short-circuits the relay J at the contact 154 and thus releasesthe said relay. It it werenot for the fact that the impulse 'selector hasreac'hed itsnormal position by this one step,the ims pulse relay J `would operate again, at once,` in the above mentioned icircuit and the `cycle et operations would` be repeated until the impulse selector has attained its normal position. At any rate, when ther normalposition of the impulse selector is reached, the relay T, is energized via battery, contact 151, wipers 152and 156,*bank contact 15T, winding l oi relay Tzbank `'contact '158, wiper 159, contacts 160, 142 ijand141 `to earth. The lrelay T2 opens lthe contact 161 and closes 162. This short-circuitsthe relay R and connects up the winding II of the re lay T2. The relay R` allowsit's armature to drop, and releases the position selector, the keys and the impulse selector,I so that these cany beiused for a new connection.

The setting of the numerical impulse receiver lGlV is effected inthe known man- `-ner.,. Theclearing signal is` given,` in this embodiment, through i a Special 4lead` c. When the called subscriber hangs up his receiver, relay Al on the first selector LGW' operates by increased currentover the associated third conductor as hereinbeforc` de.- scribed, and by closing the contact 163, connects Aup the clearing signal lamp SLT The connection is cutoff by taking `'the an- 'relay TR2 energized through :the contact 171, and the resistance 172. The rotary magnet of the iirst pre-selector IVV is connected up through the Contact 173. The setting lof the pre-selecting devices and the taking into use and setting of the numerical impulse receiver, which can also be reached by the operator, Vare effected in the known manner.

After the release of the selecting devices responsive to the calling subscriber replacing his receiver, the call lamp AL., is connected up, toact as clearing signal, as follows: earth, contact 174, resistance 175, contact 176, lamp AL, to battery. Owing to the resistance 175, the call lamp AL, gives a du'lllight and thus gives the operator a clearing signalithat diiers definitely from the calling signal. In` comparison with the firstembodiment according to Fig, 1 this circuit'arrangement presents the advantage that there is -no need to use a cord circuit during a connectionbetween two automatic subscribers. As soonias the key HT has been pressed, the vanswering plug ASTI can be taken out of'thejack AKZ.

Figure 3a shows how an interrupter 176 can be connected in the circuit of lamp AL2 `in orderto give the operator a iiashclearing signal. This is desirable in 'some cases wherethe signal given by the dim illumination of thecall lamp is not suiiiciently conspicuous to attract the operators attention.

IVhat I claim and desire to protect by Letters Patent is 1. In a telephone system` two exchanges, means including an operators link circuit and directively controlled automatic switching ymeans whereby an operator can set up a connect-ionfrom a calling subscribers line inlone exchange toa line in the other exchange, Vand means whereby said operator can place the setting up vof the connection under the control of the said calling line, said 'control being exercised over a path exclusive of said link circuit.

2. In a telephone system, two exchanges, means including an operators link circuit and directively controlled automatic switching means whereb'yan operator can extend a connection from a calling subscribers line in the first exchange to a line in the second exchange, and means whereby the operator can assign the directive control of the automatic switching means to the said calling line, said control being exercised over a path exclusive or" said link circuit.

'3. In a telephone system, a calling line, an automatic switch individual to said line, a line relay for said switch normally connected to said linebut having no control over said switch, and means controlled'by an operator for placing -said automatic switch under the control of said line relay.

4. In aytelephone system, a calling line, an individual line relay normally connected to said line, automatic switching means over which said line relay has no control, and means individual to said line controlled by an operator for placing lsaid automatic switching means under the controlot said line relay.

5. In a telephonesystem, a lineterminating at an operators position, meansincluding an operators cord circuit for answering a call onsaid line and vfor extending a connection Yfrom said line to a called line, automatic switching means over which said calling line has vr"no control, a spring `iack at said voperators position individual to said calling line and means whereby the operator can place said automatic switching means underthe .control of said calling line by insertinga plug of her cord circuit into said springjack. y

6. In a telephone system, an operators position,`a plurality oi" trunks terminating thereat. means for taking any one of said trunks for use, an impulse emitting device common to said trunks, means for 'connecte ing said device with any one of said trunks when the latter is taken for use, and means for transmitting a series of impulses from said device tothe last `mentioned trunk after the same is connected with said device, the numberof impulses inthe series being dependent upon the trunktaken for use.

7. In a telephone system, an operators position, a vplurality oi trunks terminating thereat, a plurality of automatic directively controlled switches. means for taking any one of said 'trunks for use. means responsive thereto for associating the trunk taken for use with one of said switches, an impulse emitting device, means for 'associating said device with any one of said trunks when the latter is taken for'use, means for transmitting a vseries ofimpulses from said device to the 'last mentioned switch, the number of impulses in the series dependent upon the 'trunk taken for use.

8. In a telephone systemQa trunk line, a plurality of incoming lines at the'originating'end of said trunk line, ya corresponding plurality of outgoing lines l at the distant end, an impulse sending 'device at the orig- 1,470,451 i p i "7 inating end of said trunk line7 a correspond ing plurality of outgoing lines at the distant end, automatic switching mechanism responsive to the seis/iure of any incoming line for connecting such iine to said trunk, an impulse sending device7 automatic switching mechanism for` connecting said device to the incoming line in use, a selector at the distant end of said trunk, and means 'for automatically operating said device subsequent to the connect-ion thereof with the incoming line for transmitting a series of impulses over the trunk to operate said selector to connect said trunk With the out going line which corresponds to the incoming line in use. y

10. In a teiephone system, a trunk line,

a plurality of incoming lines at the originating end of said trunk line, a corresponding plurali'ty of outgoing lines at the distant end, automatic switching mechanism responsive to the seizure of any incoming line for connecting such line to said trunk, an impulse sending device, automatic switching mechanism for connecting said device `to the incoming line in use, a selector at the distant end of said trunk, and means responsive to the connection ctt the incom ing line to the trunkor'the connection of y the device to the incoming line, Whichever is last established, `for operating said device to transmit a series of impulses over the trunk to operate said selector to connect said trunk With the outgoing line which corresponds to the incoming line in use. i

Signed by me atSiemensstadt, Germany this th day of October 1921.

THEODOR KORTHUER. 

